16 March 2018

unid 32-bit secondary protocol

The analysis is related to a 3G-HF STANAG-4538 transmission in which the traffic service is “Circuit Mode” and spotted on 7961 KHz/USB, 188-110A Serial is used as the traffic waveform. After demodulation of 188-110A, the stream obtained shows a series of data blocks, corresponding to the transmitted bursts, characterized by a 32-bit length period which is due to the headers of each block (Fig. 1). Comparing the headers gives a common structure of 120 bytes that differs by 32 bytes (Fig. 2).